Some animals see differently
than we do. Some animals, like bees, have cones for colors we can't see. Some
animals have developed a highly-advanced senses of smell or specialized hearing
abilities such as echolocation. Others have acquired eye adaptations for
improved night vision
The most interesting feature of nocturnal animals is the size of their eyes.
Large eyes, with a wider pupil, larger lens and increased retinal surface
collect more light. Some animal species have evolved tubular eyes as a means of
increasing their size. Many nocturnal animals cannot move their eyes within the
orbit. Instead, they have evolved extraordinary rotational ability in the neck.
Owls, for example, can rotate their neck through 270° & this aids their vision.
Some animals of the night have acquired a spherical lens and widened cornea to
compensate for reduced eye movement. This combined with a wide cornea increases
the animals field of view allowing the head and eyes to remain motionless.
Mirrors Add Intensity, Eyes glow in the dark
On a dark night, flash a bright light at your dog or cat's eyes & you notice
that their eyes glow in the dark. It is the tapetum lucidum (meaning "bright
carpet"), an adaptation for night vision. The tapetum is a thick reflective
membrane, 15 cells wide, directly beneath the retina. It collects and re-emits
light back to the retina a second time, giving the rods a second chance to
absorb the image information, thus maximizing the little light available to
them. As this light is reflected off the tapetum, the animal's eyes appear to
Although nocturnal animals see mostly crude or imperfect shapes, outlines and no
colors, by maximizing their sensitivity to low light levels with the above
adaptations, it is enough for them to hunt, feed and survive in the dark of
In The Daylight
Most nocturnal animals are often inactive during the day to avoid
over-stimulating their highly sensitive eyes. Nocturnal animals have specialized
pupils to shut out damaging bright day light. Nocturnal animals dilate their
pupils to their circular maximum at night.